Patients with complete lower limb paralysis after spinal cord injury (SCI) have been given the ability to walk again, it was reported this week. In work published in Nature Medicine, a 29-year-old male, paralysed after an accident, was able to step independently with the help of epidural electrical stimulation (EES).
As the authors explain, the work reveals that spinal sensorimotor networks that are functionally disconnected from the brain because of SCI can be engaged via EES to restore robust, coordinated motor activity in paralysis sufferers.
Over the course of 113 multimodal training sessions, spanning 43 weeks, the patient achieved remarkable milestones that included walking the length of an American football field with occasional assistance. By the end of the training period, he had gained improvements in leg control in such a manner that he was able to walk independently on a treadmill, and even over ground with the aid of hip stabilisation from a trainer. Videos of his progress can be found here, and here.
In another paper, four young patients, refractory to locomotor training alone, received EES during rehabilitation for traumatic, motor complete spinal injuries. Two patients were able to achieve over-ground walking using a walker or horizontal poles (278 sessions over 85 weeks, and 81 sessions over 15 weeks, respectively). All four patients achieved independent standing and trunk stability, but more study is being invested in ascertaining whether the difference in outcome among the four patients was due to sensory sparing or other variables.
Crucially, patients in both studies had epidural electrical stimulators implanted surgically at least two years after injury, and limb movement was only possible when the stimulator was activated. In addition, while all patients had total SCI – meaning no voluntary movement below the level of their injury – their spinal injuries were not classed as total severing. The patient in the first study, and two in the second had American Spinal Injury Association (ASIA) grade A impairment (no sensory or motor function below the injury), while two others in the second study had some “spared sensation” (grade B).
Both works stem from earlier research by Professor Susan Harkema and colleagues at the University of California Los Angeles, USA, who reported that a paralysed patient who underwent EES could recover a number of motor functions.
Looking forward, additional research is now being focused on learning just how electrical stimulation and rehabilitation interact, and whether the approach could help others.